Supplementary Material for: Development and Validation of a Nomogram to Predict Airway Fibrostenosis in Tracheobronchial Tuberculosis

Background: Airway fibrostenosis, a severe complication of tracheobronchial tuberculosis (TBTB), causes respiratory morbidity including atelectasis, pneumonia, and respiratory failure. Early risk prediction remains challenging due to the lack of validated assessment tools.

Methods: This retrospective cohort study analyzed TBTB patients undergoing bronchoscopic interventions between January 2021 and June 2024 with 6-month follow-up. A Cox regression model was developed in all 305 patients, internally validated with 1,000 bootstrap resamples. Performance was evaluated via C-index, ROC-AUC, calibration, and decision curve analysis. Kaplan-Meier analysis was used to stratify groups, with log-rank tests assessing differences.

Results: Airway fibrostenosis incidence was 60.33% (184/305). Eight independent predictors were identified: symptom duration, affected lung lobes, diabetes, multiple TBTB types, bronchoscopic intervention frequency, initial sputum acid-fast bacilli smear grade, neutrophil-to-lymphocyte ratio, and CD8+ T-cell count. The nomogram demonstrated strong discrimination (C-index 0.77, 95%CI 0.75-0.81) with increasing predictive accuracy over time: 6-week AUC 0.773 (0.708-0.838), 8-week 0.792 (0.740-0.844), 12-week 0.830 (0.782-0.878), and 16-week 0.883 (0.842-0.923). High-risk patients exhibited a significantly higher probability of developing airway fibrostenosis compared to low-risk patients (P<0.001). Calibration and decision curve analyses confirmed clinical utility.

Conclusions: This validated nomogram effectively predicts airway fibrostenosis risk in TBTB patients, enabling early identification of high-risk individuals for targeted interventions.